Generally, golf balls have been classified as solid balls or wound balls. Solid balls are generally comprised of a solid polymeric core and a cover. These balls are generally easy to manufacture, but are regarded as having limited playing characteristics. Wound balls are comprised of a solid or liquid-filled center surrounded by tensioned elastomeric material and a cover. Wound balls generally have good playing characteristics, but are more difficult to manufacture than solid balls.
The prior art is comprised of various golf balls that have been designed to provide optimal playing characteristics. These characteristics are generally the initial velocity and spin of the golf ball, which can be optimized for various players. For instance, certain players prefer to play a ball that has a high spin rate for playability. Other players prefer to play a ball that has a low spin rate to maximize distance. However, these balls tend to be hard feeling and difficult to control around the greens.
Manufacturers have molded layers around a solid center by placing a preformed center between two blocks of core material in a spherical compression mold, and closing the mold. This process, however, provides little control over the ultimate placement of the center within the golf ball core. Large variations in the location of the center can result.
The prior art also provides for the manufacture of double cover golf balls. This is generally accomplished by injection molding a first and then a second cover layer around a core. This system, however, requires complex injection molds, usually with retractable pins within the mold to properly position the core. Moreover, this system generally works better with thermoplastic materials.
Therefore, what is desired is a method and apparatus for molding multi-layer cores or multi-layer covers that ensures properly centered balls.